I never understood something. Why do dogs that are in training have a 'do not pet' vest? Don't you want people to come up to them so that they become socialized? Sorry if I sound ignorant and I hope you don't mind me asking...?

His coloring is gorgeous though. I'm glad training is going well C:

Socialization does not mean that the dog has to INTERACT with humans, dogs, etc. It means that dogs need to be used to these things in their environment and accepting of them being around. If the OP is training this dog as a service dog, you DON'T want the dog thinking that people are there to pet him. He will be WORKING and expected to completely ignore all other stimuli, so it is easier on training to keep people away and you can move the dog closer to them as you're proofing attention and commands with more distractions.